Salt & Nutrient Management Plan Pajaro Valley Water Management Agency
Stakeholder Workshop #2March 28, 2013
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Agenda
• SNMP Overview (10 min)• Existing Groundwater Conditions (30 min)• Loading Analysis Approach – Nutrient loading risk analysis/findings (1 hr)– Salt loading risk analysis/findings (30 min)
• Assimilative Capacity Discussion (15 min)• SNMP Objective Development Discussion (30 min)• Stakeholder Next Steps (10 min)
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9 am – 1pm
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SNMP Development Process
Primary Tasks Schedule
Task 1. Stakeholder Outreach Stakeholder Meetings at critical milestones
Task 2. Conceptual Model Draft included
Task 3. Salt and Nutrient Loading Analysis Draft included
Task 4. Assimilative Capacity Estimate Draft Fall 2013
Task 5. Develop or update objectives Draft Fall 2013
Task 6. Develop or update priority program/projects Draft Fall 2013
Task 7. SNMP Monitoring Plan Draft Spring 2014
Task 8. Conduct anti degradation analysis Draft Spring 2014
Task 9. Complete SNMP Summer 2014
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Stakeholder Feedback Process
• Plan developed in iterative sections• Drafts vetted with stakeholders• Go to PVWMA website for report and
Stakeholder comment formhttp://www.pvwma.dst.ca.us/board-and-committees/salt-nutrient.php
• Comments must be submitted in writing, compiled on comment site
• Comments due by 04/12/2013• Responses tracked and available to all
Existing PVGB Groundwater Conditions
Approach• Analyze existing groundwater data
• 295 PVWMA Production & Dedicated Monitoring Wells• 14 City of Watsonville Production Wells
• Calculate statistics by site and constituent for the 10-year period: 2002-2011
• Map statistical results and then interpolate the decadal average and maximum concentrations using Inverse Distance Weighted method
• To protect the confidentiality of the well owner, results are maps that show interpolated concentration contours, but do not display individual well data
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Inverse Distance Weighted Method
• Predicts values at unmeasured locations based on measured values surrounding the prediction location.
• Local influence from measured data diminishes with distance.
• Method is being used to develop SNMPs elsewhere in the state.
Metered & Unmetered
Wells
[TDS] Range (mg/L) acres (%)0-450 35,300 (52%)
>450– 1000 27,900 (41%)>1000– 1800 3,550 (5%)
>1800 637 (1%)
GroundwaterAverage TDS
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[TDS] Range (mg/L) acres (%)0-450 29,300 (43%)
>450– 1000 30,500 (45%)>1000– 1800 6,950 (10%)
>1800 900 (1%)
GroundwaterMaximum TDS
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[Cl] Range (mg/L) acres (%)0-100 55,500 (82%)
>100– 250 8870 (13%)>250– 500 2600 (4%)
>500 644 (1%)
GroundwaterAverage Cl
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[Cl] Range (mg/L) acres (%)0-100 52,900 (78%)
>100– 250 10,400 (15%)>250– 500 3170 (5%)
>500 1200 (2%)
GroundwaterMaximum Cl
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[NO3] Range (mg/L) acres (%)0-10 25,500 (38%)
>10– 45 28,400 (42%)>45– 100 10,500 (16%)
>100 3,260 (5%)
GroundwaterAverage NO3
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[NO3] Range (mg/L) acres (%)0-10 24,600 (36%)
>10– 45 23,100 (34%)>45– 100 12,600 (19%)
>100 7,410 (11%)
GroundwaterMaximum NO3
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PVGB Groundwater Condition Summary
PVGB Area mapped: 67,500 acres
Constituent ThresholdFraction acreage above threshold
AVERAGE (%)
Fraction acreage above threshold
MAX (%)
TDS 1000 mg/L 6% 11%Chloride 100 mg/L 18% 22%
Nitrate-NO3 45 mg/L 21% 30%
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SNMP Pollutant Loading Analysis
RISK ANALYSIS APPROACH• Relative risk for each primary source • Identify primary factors driving potential loading• Identify available data to inform factor
contribution• Categorize relative contribution of sources based
on factors in risk matrices• Generate spatially explicit distribution of relative
risk within PVGB area.
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SNMP Pollutant Loading Analysis
ADVANTAGES• Relative risk for each primary source • Sensitive to same inputs as complex models, but
less debate on accuracy.• Transparent and easy to communicate• Focus confidence on relative risk designations • Informs priority locations/practices where
improvements would be most beneficial
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Soil [NH4+, NO3
-]
Atmosphere [N2(g)]
Groundwater [NO3-]
Relevant components of the NITROGEN CYCLE
Plants [N organic]
mineralizationuptake
Air Pollution [N2O]
Septic/sewer systems[NH4
+, NO3-]
deposition
applications leaks
Animal waste[NH4
+, NO3-]
fixation
leaching
Fertilizer[NH4
+, NO3-]
deni
trifi
catio
n
mineralization
Controllable sources
Key reservoirs
KEY
process
Upgradient sources
Downgradient migration
Irrigation water[NH4
+, NO3-]
Stormwater[NH4
+, NO3-]
runoff
Nitrogen – NO3 Risk Analysis
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Agricultural Fertilizer NO3 Loading Risk Analysis
Factors evaluated• Soil water holding capacity• Land use patterns• Annual irrigation volumes • Amount of N applied as fertilizer
Data sources used• NRCS Soil survey• PVWMA Ag crop land use data (2012 and 2011)• PVWMA and MCWRA water usage data and grower
surveys• NASS survey data and published literature values
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Agricultural Fertilizer NO3 Loading Risk Analysis
Soil water holding capacity• NRCS data used for 1-100 cm soil depth• 4 categories based on amount of water held by soil, soil
texture data and slope• Categories are specific to the diversity of soil conditions
within the Pajaro Valley
Categories• Low – capacity to hold up to 0.75 AF per acre• Moderate – capacity to hold 0.75 – 1.25 AF per acre• High – capacity to hold 1.25 – 1.5 AF per acre• Very High – capacity to hold 1.5 – 2.3 AF per acre
Relative Soil Water Holding Capacity
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Agricultural Fertilizer NO3 Loading Risk Analysis
Land use patterns• PVWMA Ag land use data averaged for 2011 – 2012• 6 categories based on crop groups specific to agricultural land
use within the Pajaro Valley
Categories• Vegetable row crops including artichokes, broccoli, cabbage,
cauliflower, celery, lettuce, spinach and other leafy greens• Horticulture nurseries including bulb production facilities, cut flower
operations, landscape plants and transplant operations• Strawberries• Caneberries• Deciduous trees – orchards• Other agriculture production including vines, grapes and
miscellaneous crops
Land Use Category Acres %Vegetable Row Crops 9,138 13
Horticulture Nurseries 1,343 2Strawberries 7,994 11Caneberries 5,003 7
Deciduous (Orchards) 2,179 3Other, Unknown Ag, Vines/Grapes 1,142 2
Non-agriculture land uses 43,158 62Total 69,957 100
PVGB Ag Land Use
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Agricultural Fertilizer NO3 Loading Risk Analysis
Irrigation intensity• PVWMA usage data, MCWRA usage data, and published
literature data sources• 3 categories based on range of values by crop group• Categories are specific to the irrigation requirements based
on both crop and cool climate within the Pajaro Valley• Individual agriculture operations may have usage patterns
different than values used for each crop groupCategories
• Low – usage of 0.5 – 1.7 AF per acre, such as grapes and orchards• Moderate – usage of 1.8 – 2.3 AF per acre, such as strawberries,
caneberries and other acreage on drip irrigation• High – usage of 2.4 – 3.0 + AF per acre, such as double cropped
vegetable row crops and other acreage utilizing sprinkler irrigation
Irrigation category % of Ag landHigh 39
Moderate 49
Low 12
Agricultural land 26,799 acres
Non-agricultural land 43,158 acres
Irrigation Intensity
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Agricultural Fertilizer NO3 Loading Risk Analysis
Agriculture crop fertilizer use • NASS surveys, PVWMA surveys, and published literature data
sources• 4 categories based on a range of values by crop group• Categories are specific to the diversity of crops and the soil fertility
conditions within the Pajaro Valley• Individual agriculture operations may have usage patterns different
than values used for each crop group
Categories• Low – usage of 35 – 75 lbs. N per acre, such as grapes, certain horticultural
operations and miscellaneous crops• Moderate – usage of 76 – 149 lbs. N per acre, such as orchards, caneberries• High – usage of 150 – 250 lbs. N per acre, such as strawberries , vegetable row
crops and certain horticultural operations• Very High – usage of over 250 lbs. N per acre, as may occur under certain
conditions of crop production
Fertilizer category Meas.% ag land
Expect%
Very High 29
High 69 40
Moderate 27 27
Low 4 4
Ag land 26,799 acres
Non-ag land 43,158 acres
Fertilizer Intensity
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Agricultural N Risk Matrix
Irrigation Intensity Fertilizer Intensity Soil Water Holding Capacity
Based on crop type
Agricultural Fertilizer NO3 Loading Risk Analysis
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Agricultural N Risk Matrix
Water Holding Capacity (AF) Water
(AF/acre/year) Fertilizer
(lbs. N/acre/year) Very High (1.5 - 2.3)
High (1.25 - 1.5)
Mod (0.75 - 1.25)
Low (< 0.75)
High (2.4 - 3.0+)
High (150 – 250+) MOD RISK HIGH RISK HIGH RISK HIGH RISK
Mod (1.8 - 2.3)
High (150 – 250+) MOD RISK MOD RISK HIGH RISK HIGH RISK
Mod (1.8 - 2.3)
Mod (76 - 149) LOW RISK MOD RISK MOD RISK HIGH RISK
Low (0.5 - 1.7)
Mod (76 - 149) LOW RISK LOW RISK MOD RISK MOD RISK
Low (0.5 - 1.7)
Low (35 - 75) LOW RISK LOW RISK LOW RISK LOW RISK
Agricultural Fertilizer NO3 Loading Risk Analysis
Ag nitrate loading risk Acres % of Ag Land
HIGH 14,312 53%MODERATE 10,224 38%
LOW 2,263 8%Total Ag land 26,799 100
AgricultureN Risk
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Septic N Risk Analysis
Factors : presence and soil typeSeptic GIS data Monterey and SC CoMonterey Co data generated using CAD plans by 2N. 4500 of septic systems in PVWMADensity exceeds 400 units/sq mi in some locations
Septic nitrate loading riskNumber of
septic systemsSC/Mo %
HIGH 1889 1023 / 866 42
MODERATE 2152 1955 / 197 48
LOW 431 311 / 120 10
Total 4472 100
Septic N Risk Analysis
Septic risk # SCC /MoC %
HIGH 1023 / 866 42%
MODERATE 1955 / 197 48%LOW 311 / 120 10%Total 4472 100%
SepticN Risk
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Sewer N Risk Analysis
Factors : presence and soil typeSewer GIS data Monterey and SC CoMonterey Co data generated using CAD plans by 2N. 146 miles of sewer lines in PVWMA
Sewer riskTotal
Length (miles)
%
HIGH 19.4 13%
MODERATE 72.7 50%
LOW 53.7 37%Total 145.8 100%
SewerN Risk
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Surface water infiltration N Risk Analysis
Q3 nitrate-NO3 MEAN concentration (Figure 4.7) Stream bed
vertical Very Low Low Mod High
conductivity < 10 mg/L 10 > 45 mg/L 100> 45 mg/L > 100 mg/L Very High LOW RISK MOD RISK HIGH RISK HIGH RISK (>3.0 m/day)
High LOW RISK MOD RISK HIGH RISK HIGH RISK (1.0-3.0 m/day) Mod LOW RISK MOD RISK MOD RISK MOD RISK (0.25-1.0 m/day) Low LOW RISK LOW RISK LOW RISK LOW RISK (0.01-0.25 m/day)
Very Low (<0.01 m/day) LOW RISK LOW RISK LOW RISK LOW RISK
Factors : stream bed conductivity and mean Q3 [NO3]
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StreamflowInfiltration
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Surface water infiltration N Risk Analysis
StreamflowN Risk
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• Agricultural Irrigation o Potential opportunity to manage fertilizer appso Similar outcome as fertilizer risk
• Riparian land use risko Buffer approach
• Urban storm water runoffo Localizedo Low recharge in Sloughs
• Atmospheric o Uncontrollable
• Animal Wasteo Minimal presence
Subordinate Sources N loading
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N loading ACROSS sources
N Source Average annual N load to groundwater (t/yr)
Agricultural land use 1,742
Septic systems 67
Sewer systems 66
WWTP 80
Streamflow infiltration 746
Total PVGB 2,700 t/yr
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Agriculture: 1742 t N/yr
Mass of N leaching to gw per year per acre * acres of Ag in PVGB
130 lbs N/acre/yr x 26,799 acres of ag
• 134 lbs N/acre/yr (Viers et al 2012; study area average)• 123 lbs N/acre/yr (Viers et al 2012; Mo Co area average)
N loading ACROSS sources
Tulare/Salinas Basins (Viers et al 2012)
PVGB
High fertilizer demand crop distribution (% of ag land)
40 % 67%
Ave fertilizer application rate(lbs N/acre of ag land /yr)
145 180
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SEWER (67 t N/ yr)• Fraction of N per person lost (1-25%)
25% of 55,000 people waste
SEPTIC (66 t N/yr)• Fraction of N per person lost (85%)
16,100 people on septic
WWTP (80 t N/yr)• 6.6 million GPD treated, 50% infiltrated @ 16 mg/L NO3
Stream flow recharge (746 t N/yr)• USGS annual recharge (AF/yr) * NO3 SW conc.
18,300 AF/yr * 30 mg/L
N loading ACROSS sources
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Sources in PVGB• Seawater Intrusion• Irrigation practices• Surface water recharge
Salt loading risk analysis
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• Seawater IntrusionSeawater Intrusion
Risk
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Plant Growth
SALT leaching
Evapotranspiration
Soil SALT adsorption
SALT leaching
Evapotranspiration
Soil SALT adsorption
Plant Growth
Aquifer SALT
Aquifer SALT
Irrigation volumes
SALT CYCLING ON IRRIGATED LAND
HIGH
HIGH
Low
Low
HIGH
HIGH
HIGH
HIGH L
Salt content of irrigation waterHIGH Low
Low
Low
Low
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Factors• Annual water use• Irrigation water TDS content• Soil water holding capacity
Irrigation salt loading risk
Water Holding Capacity (AF)
Water USE Irrigation Water TDS Very High High Mod Low
(AF/acre/year) (mg/L) (>1.5) (1.25 - 1.5) (0.75 - 1.25) (< 0.75)
All categories High MOD RISK HIGH RISK HIGH RISK HIGH RISK (>1000) High Mod MOD RISK MOD RISK HIGH RISK HIGH RISK (2.4 - 3.0+) (450-1000) Mod Mod LOW RISK MOD RISK MOD RISK HIGH RISK (1.8 - 2.3) (450-1000) Low Mod LOW RISK LOW RISK MOD RISK MOD RISK (0.5 - 1.7) (450-1000)
All categories Low LOW RISK LOW RISK LOW RISK LOW RISK (<450)
Irrigation salt risk Acres %
HIGH 6,647 25
MODERATE 9,669 36LOW 10,285 39
Total Ag land 26,601 100
IrrigationSalt Risk
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Surface water infiltration SALT Risk Analysis
Factors : stream bed conductivity and mean Q3 [TDS]
Q3 TDS MEAN concentration (Figure 4.10) Stream bed vertical Very Low Low Mod High
conductivity < 450 mg/L 1000 > 450 mg/L 1800 > 1000 mg/L > 1800 mg/L Very High LOW RISK MOD RISK HIGH RISK HIGH RISK (>3.0 m/day)
High LOW RISK MOD RISK HIGH RISK HIGH RISK (1.0-3.0 m/day) Mod LOW RISK MOD RISK MOD RISK MOD RISK (0.25-1.0 m/day) Low LOW RISK LOW RISK LOW RISK LOW RISK (0.01-0.25 m/day)
Very Low (<0.01 m/day) LOW RISK LOW RISK LOW RISK LOW RISK
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StreamflowSalt Risk
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Assimilative Capacity Discussion
• Required Task of SNMP• Intent of task is to identify areas of concern and areas
where standards are met• No specific GW standards for PVGB
• Clarification from Regional Board requested
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SNMP Objective Development
Useful strategy implementation objectives are:• Future vision statements and time frame• Measurable• Used to communicate and track progress toward future
vision• Used to guide strategy/project development and
prioritization• Used to guide monitoring needs, purpose and use of data
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Pajaro River Watershed IRWM WQ Goal and ObjectivesWater Quality Goal: Protect and improve water quality for beneficial uses consistent with regional community interests and the RWQCB basin plan objectives through planning and implementation in cooperation with local and state agencies and regional stakeholders.
Water Quality Objectives:1. Meet or exceed all applicable groundwater, surface water, wastewater, and
recycled water quality regulatory standards.2. Identify and address the drinking water quality of disadvantaged communities
in the Pajaro River Watershed.3. Protect groundwater resources from contamination including salts and
nutrients.4. Address impacts from surface water runoff through implementation of Best
Management Practices or other surface water management strategies.5. Meet or exceed delivered water quality targets established by recycled water
users.
SNMP Objective Development
Actions
Join a gym Physical Health
Weight (lbs)
Diet, ExerciseGenetics
Jog (mi/wk)
Increase sewer
Groundwater Quality
NO3 distr [mg/L]
Septic LeakageLegacy pollution
Septic density (# area)
Alternative Objectives
Protect groundwater resources from contamination including salts and nutrients.
Reduce the distribution of maximum groundwater NO3 concentrations to < 15% of total PVGB area by 2034.
Reduce septic density to 40/sq mi in Freedom and Corralitos by 2034.
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Increase sewer
Groundwater Quality
NO3 dist [mg/L]
Septic LeakageLegacy pollution
Septic density (#/area)
Protect groundwater resources from contamination including salts and nutrients.
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Challenges with measurable objectives
• Difficulty and reluctance to prioritize if results in missed opportunities
• Political or regulatory implications if targets are not achieved.
• Broader community vision but PVWMA lacks authority to require priority strategies to be implemented.
• Others?
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Stakeholder Objectives Feedback
Desired approach
Concerns or desires
Potential areas of objective development focus by team
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Next Steps for Stakeholders1. Download Draft Ch1.-5 of SNMPhttp://www.pvwma.dst.ca.us/board-and-committees/salt-nutrient.php
2. Submit comments on google docs form by APRIL 12.
3. Comments in writing, specific recommendations of changes required.
4. Team will respond on Google Doc by April 30 and alert Stakeholders
5. Next stakeholder meeting and draft sections in late summer/early fall
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SNMP Development Process
Primary Tasks Schedule
Task 1. Stakeholder Outreach Stakeholder Meetings at critical milestones
Task 2. Conceptual Model Draft included
Task 3. Salt and Nutrient Loading Analysis Draft included
Task 4. Assimilative Capacity Estimate Draft Fall 2013
Task 5. Develop or update objectives Draft Fall 2013
Task 6. Develop or update priority program/projects Draft Fall 2013
Task 7. SNMP Monitoring Plan Draft Spring 2014
Task 8. Conduct anti degradation analysis Draft Spring 2014
Task 9. Complete SNMP Summer 2014
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